What is considered an active ingredient in sunscreen?

The correct answer indicates that all types of blockers, both chemical and physical, are considered active ingredients in sunscreen. Sunscreen formulations typically include active ingredients that either absorb UV radiation (chemical blockers) or reflect and scatter it (physical blockers).

Chemical blockers, such as avobenzone or octisalate, work by absorbing UV rays and converting them into heat, which is then released from the skin. In contrast, physical blockers, like zinc oxide and titanium dioxide, create a physical barrier on the skin that deflects and scatters harmful UV rays away from the skin’s surface.

Since both categories are integral to the functioning of sunscreen and contribute to its effectiveness in protecting against the harmful effects of sun exposure, recognizing both as active ingredients is essential in understanding how sunscreen works. This knowledge emphasizes the importance of selecting a sunscreen that effectively combines chemical and physical blockers for comprehensive UV protection.